Sinking pier, caisson, and the like



Aug. 21, 1934. D. E. MORAN v SINKING PIEiR, CAISSON, AND THE LiKE File d June 15, 1952 4 Sheets-Sheet 1 0m X X X mmmm @ 1, (D g/fz 000000m 00 00 0 Q 000000m VA X 0m X w H INVENTOR jlq/v/a EflfD/BAM Y- I ATTORNEYS SINKING PIER, CAISSON, AND THE LIKE Filed June 15, 1932 4 Sheets-Sheet 2 'ug. 21, 1934. D. E. MORAN 1,971,046

AugQZl, 1934. D. E. MORAN 1,971,046

9111x1119 PIER, CAISSON, AND 1119,1111:

Filed June 15, 1952 4 Sheets-Sheet a INVENTOR DAN/EL Z7. M/ew/v.

' ATTORNEY-3 Patented Aug. 21, I934 UNITED STATES PATENT OFFICE m6 PIER, CAIBSON,AND mm mammmmr.

motion June 15, 1932, Serial No. 17,839 3 Claims. (01. 1-41) The invention relates to improvements in methods of constructing and handling bridge piers, caissons, foundations and similar structures which are to be sunk in water and by excavation through I mud and other materials.

The invention is applicable to a variety of situations, but probably finds its greatest economy in the largest type of pier foundations under water.

The accompanying drawings illustrate struc- 10 tures and method: embodying the invention.-

rimiisaplanofadredgingcaissonadapted to form the base of a bridge pier;

Figs. 2, 3 and 4 are vertical sections of the same on the line 2-2, Fig. l, in difl'erent' stages;

Fig. 5 is a vertical section of the lower part oi a pier in the final stage:

Figs. 6 and 7 are a vertical section and plan respectively showing the invention applied to a erent type of pier. as Fig. 1 illustrates a dredging caisson of recto-n solar shape, the'body 11 being composed of con-- crete, brick, stone or the like, referred to herein as masonry, through which extend vertical dredgng Shafts lined with steel tubes 12. Such a B5 caisson is built partly on shore and floated to the site and there sunk, to rock, clay or other support available.- During the floating of the caisson the shafts 12 are open at the bottom. closed at the tops somewhat above the masonry so by caps 13 and supplied with air under pressure as by air pipes 14.

The number of shafts and their size in cross section are sumcient to float the structure. For this purpose the air pressure may be sufficient to force the water downto the level 15, Fig. 2, substantiallv at the bottom of the shafts 12. In other circumstances, the air pressure may be less, permitting the water to rise in the shafts or air chambers. For-example, for every 56 square feet of concosts in plan, there may be a shaft of feet diameter. In that case, air extending to the bot toms of the shafts as in Fig. 2, would provide scicnt buoyancy to float a cellular concrete pier base having dimensions in plan of 57 feet by iii feet and extending from the bottom of the shafts to water level. y

me air line is shown simply diagrammatically; the necessary compressors, couplings and valves being assumed for operation in the manner herein described.

when the caisson is landed on bottom on material of sufficient supporting power to render the use of flotation chambers unnecessary, the shafts 12 are to be used for dredging mud, sand and other material through which the caissonis to be lowered to the sub-foundation. Such dredging shafts are distinguished from the working shafts of ordinary pneumatic caissons in several respects. They must be open top and bottom and of a size large enough to pass a dredging bucket such, for example, as the clam-shell digger 16.

Fig. 4, must be unobstructed and generally of substantially uniform cross section from the top to the bottom excepting for a slight flare and changetorectangular shape at the bottomtoform the cutting edges 17. Diggers are made in a variety of sizes and types. But the clam-shell type and the" larger sizes are generally used in this class of work. I

The total air space required for flotation being determined, the larger shafts have the double advantage of being fewer in number and permitting the use of larger and therefore faster dredgers.

when the caisson has been floated to the site of the pier it must be sunk and located on the bottom with accuracy. See Fig. 3. For this purpose the air pressure in the shafts is reduced and the water permitted to rise. The left-hand 00 chamber shows the partial release of air pressure and rise of water which serves to lower the caisson. The covers 13 are removable and the shaft 12 is made in sections of say five-foot heights.

As the structure is added to and therefore sinks 86 deeper the covers are removed from time to time (as at the right in Fig. 3), the shaft is progressively extended by one or more sections and the cover and air connections replaced, and the chamber again filled with air to the desired ex-- tent. The center chamber (Fig. 3) shows this situation.

As the sinking. proceeds, the masonry may be built up in the form of a finished pier. Or this building up may await the complete sinking of the caisson. In either case it is advisable to provide a cofferdam l8 surrounding the caisson and to extend it up, like the air shafts, and main-' tain it always above water level. This may be of any usual construction, generally with interior bracing. Its principal function in connection with the present invention is to safeguard the caisson against tilting.

.Where the depth is greater than the width of a floating structure, there is a tendency to capsize and to assume a position in which the least dimension is vertical. As the caisson described I is sunk and the water level rises above the top of the caisson, the upwardly extending cofl'erdam provides an air space which maintains the car's- 110 which can be used for the given height oi cofl'erdam. The shell or coflerdam in such cases is what keeps the caisson afloat.

In applicant's case, however, it is the shafts. wholly or partly capped and air-fllled, which provide the buoyancy, and which permit the use oi a coflerdam oi comparatively short height and light bracing and weight, serving chiefly to safewith the tops of the chambers anti 0! the masonry above water, floating it to the pier site and gradually extending said chambers and concrete upward and sinking said structure, the flotation chambers during the sinking being uncapped and extended and recapped in succession so as to retain enough of them capped to float the structure while extending the others.

2. In the building of submarine piers or the like, the method which consists in building the lower portion of masonry with flotation chambers open at the bottom, extending through the masonry and closed at the top and oi an aggregate cross-section to sustain the masonry afloat with in top above water when the mm m, fllled with air, floating said lower portion to the site oi the pier, sinking the structure gradually by building up the masonry and extending said chambers upward correspondingly so as to sustain the structure afloat while increasing its height, continuing the process until the structure reaches the desired height, the flotation chambers during the sinking being uncapped and extended and recapped in succession so as to retain enough of them capped to float the structure while extending the others.

3. In the building of submarine piers or the like, the method which consists in building the lower portion of masonry with flotation chambers open at the bottom, extending through the masonry and closed at the top floating said lower portion to the site of the pier, sinking the structure gradually by providing a coflerdam extending above it so as to assist its flotation and to balance it and building up the masonry and extending the chambers upward correspondingly, continuing the process until the structure reaches the desired height, the flotation chambers being of an aggregate cross-section suflicient, when their tops are above water, to sustain afloat the masonry built substantially or approximately up to the level of the water, so as to require the maintenance of only a comparatively short and light extension of the coflerdam above the masonry. g

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